This invention relates generally to supplementary security devices for conventional doors and particularly to a simple, low cost portable security device for precluding normal opening of a door.
Conventional lock arrangements for doors have a bolt which engages an opening in a strike plate that is secured to the doorjamb. It is well known that conventional key-operated bolts and strike plate arrangements are often easily defeated by the use of a thin tool or piece of plastic. This is especially true in doorframes that do not include a stop in the doorjamb that conceals the door/doorjamb interface. It is also well known that the security locks used in hotel rooms and the like are not "dead bolts" in that they may be opened from the outside with a key. Such security locks do, of course, provide a measure of protection and security for those in the room, while permitting the owner or other authorized personnel to enter the premises with a key in the event of an emergency or the like. It is also a known fact that the security system of any hotel or motel is necessarily impaired because of the need for servicing and cleaning when the room is vacant. Coupled with the fact that hotel and motel keys are often not returned, or are lost or misplaced, it becomes apparent that there may be a number of keys available for any particular room. To maintain security with so many keys in existence is extremely difficult. Consequently, there is a real danger that a stranger may possess a key to one's hotel room.
The prior art includes a number of devices for preventing the "jimmying" of door locks. Most of the devices require structural changes to the door or doorjamb and afford no protection against normal entry with a key. A device similar to the present invention is currently available to the public. It is of hardened steel and polycarbonate plastic and generally comprises a hook plate (for engaging a strike plate in a doorframe) is attached to a threaded bolt along which a body is slideable for engaging a closed door. A ratchet type locking device is also movable along the bolt against the body. When the body engages the door the ratchet trigger is released and the ratchet locking device is turned on the bolt via the now-engaged-threads of the bolt to clamp the body against the door. This secures the door from normal opening. The device is relatively complicated, expensive and has a tendency to resist removal due to binding of the trigger mechanism. It can be carried in a purse or briefcase and is therefore portable.
The security device of the present invention is simpler to manufacture and use, lower in cost and believed more effective in protecting against normal, nonforcible entry to the premises (by a key or simple "jimmying"). It, like the prior art device mentioned above, is not a barrier to a determined intruder who is willing to use force to break in. However, nonforcible entries are prevented. The device of the invention resists being dislodged by vibration and the like and is readily removable. The inventive device is also useful in conjunction with a small lock for securing closure elements, such as drawers to their mating frames for preventing unauthorized opening thereof.